Clinical and immunological follow-up of patients with lung and breast cancer, colon carcinoma, Ewing's sarcoma, and melanoma. Adjuvant chemotherapy and immunotherapy with BCG, C. parvum, with or without irradiated allogeneic tumor cells. Skin tests with crude tumor extracts and purified soluble fractions. In vitro assessment of immunocompetence, and of natural cell-mediated reactivity and tumor immune reactivity, by means of short-term cytotoxicity assays, mixed lymphocyte tumor cell culture, and leukocyte migration inhibition. Examination of cells from various lymphoid organs and from the tumor. Reactivity of subpopulations of lymphocytes. Related models: Natural and immune cytotoxic reactivity in the W/Fu rat gross virus-induced (C58NT)D, and in the F344 rat DMBA-induced 13762 mammary adenocarcinoma models. Cryopreservation of effector-target and inhibitory cells. Effect of X-irradiation on the antigenicity of tumor cells. Comparison of the Cr51-, H3-proline-, and IUdR125 cytotoxicity assays. Immunosuppressive activity of tumor cells. Isolation of immunosuppressive Kilham rat virus from these tumors. Immunosuppressive effects of this virus in vivo.